Help me change the feedline distance of antenna in IE3D

Well.. basically i have this structure with the feedline and the matching network. The impedance is matched properly here.
Feedline distance is 1.65mm measured from the bottom of the twin patch.

I have to shift the feedline to a distance of 2.0 mm measured again from the bottom of the twin patch. So this means.. the matching network will change.. How to calculate its new values or can IE3D give us the values directly..

Hi, sumit007:

This is a very good example you can use the FastEM Design Kit for real-time full-wave tuning and optim on IE3D V12. Following are some comments on your structure.

1. You use Extension for MMIC scheme. I would suggest you to use ADV EXTENSION scheme. It is more accurate at high frequency when dispersion is serious.
2. You define the Fmax = 16 and Ncells (cells/wavelength) = 10. It is a little bit low because the resonance is about 14.5 GHz. I changed it to Fmax = 18 and Ncells = 15. The revised file is in ant_r1.geo (or ant_r1.geo in IE3D 9.0 format).
3. This is a good example for FastEM tuning. I created the ant_r2.geo with shortened feed line. The feed line is about 50-ohms and you don't need a long one for element simulation. The ant_r2.geo contains FastEM data (only available in IE3D v12). Please open it using MGRID V12 and select PROCESS->FULL-WAVE EM DESIGN USING FastEM Design Kit. You will get some similar picture in the Fast_EM.bmp file. The example I show in Fast_Em.bmp is the optimized results with perfect matching at 14.75 GHz. You can change your goals and get the results in seconds. There might be some small noises due to not many points. However, it should be ok. You can always re-simulate the optimized geometry again to confirm the results. Best regards.

Added after 39 seconds:

I forgot to post the files. Here they are.

Thanks a lot Jian.

I have downloaded IE3D evaluation version 12. And was able to see all the geometries u have attached.

Thanks a lot for your input on the design. I have taken note of them.

Now... I am getting this problem:
When i Change the "Variables Slider" in the Fast EM design Kit.. and try to "SAVE GEOMETRY"

i am getting this error:
" MGRID MFC application has encountered an error and needs to be closed. ...."

And so i am not able to save different geometries. What can be the possible reason for this. I restarted the whole IE3D software but still i get the same error when I try to save the new geometry.

Hi, Sumit:

It is a crash caused by the optimizer of Visual C++ compiler. We have found and have it fixed. The bug fixed IE3D 12.02 is on the web. Sorry for the inconvenience. Please download the full installation or the patches again. Thanks!

Best regards,

Thanks.. I am d/l the software again.. Hopefully it will be downloaded by tomorrow... 'coz of my slow connection..

I am still getting lots of doubts..

My main aim is to change the position of the feedline (the one connecting the 2 patches, 50 ohms) from the current position (1.65mm) to different positions.
Now, if we change the position of feedline, I think there will be impedance mismatching.

So basically.. its like.. After I change the position of the feedline from 1.65mm to 2.1mm (measured from the bottom) , keeping the patch size same and also now the new position of the feedline fixed... I have to make sure that impedances are matched properly. So once impedances are matched properly, i have to find S11 parameters and the bandwidth.

So that means.. i have to optimize "some parameters" such that impedances should be matched. So how is it done ?
What is that command in IE3D which makes sure that i get the desired result.. Does it simply mean that if we get the lowest S11 parameter value at 14.75GHz then we can say that the impedances are matched properly ? (Because in our original design which was matched properly, we get the lowest S11 at 14.75GHz.. ? )
Can u pls send a tutorial link/writeup how to convey to IE3D about the same/ how to write those commands so that i can achieve my above goal.


Now.. I checked the FastEM solver file that u sent to me.
I am not sure about this - since we are changing the feedline position and then keeping the position fixed and then we have to optimize the antenna such that the impedances are matched (note that patch dimensions, and feedline location now cannot be changed for the impedance matching).. I was wondering that the length/width of the feedline connecting the two patch has to be changed for proper matching.. And also the length/width of the transformer...

However, in the FastEM file, i found that the lenght/width of the feedline is not changed for different positions. Only the tranformer length is changed (manually) so that we get S11 lowest at 14.75GHz.. Why shouldnt the length/width of the feedline be changed?

Is it because when we shift the feedline to another position, because of symmetry (that point lies on the same vertical line) so impedance will be the same everywhere on that particular line and so where ever we position the feedline, the impedance will be same. ? And hence, there is no need to put a transformer between patch and feedline.. as that will be matched in any case and also there is no need to change the length/width of that feedline..

To add more to my last post..

You said.. The example I show in Fast_Em.bmp is the optimized results with perfect matching at 14.75 GHz. You can change your goals and get the results in seconds.

My goal is --
1. I change the location of the feedline.
2. Goal = Impedances shud be matched (so is it same as saying results perfectly matchd at 14.75GHz ? or i have to define something else during optimization :( )
3. Get S11 parameter values and find bandwidth from the figure (below -10dB)


Then again change the location of the feedline.
And again get bandwidth (after the structure is matched properly)

phew.. i am totally lost..

Hi, sumit:

For the Fast_Em.bmp file, I just show you the results. The .geo file I sent you contains the FastEM full-wave results. Basically, it is a parameterized model allowing you to get real time results with some variables in your geometry. You can slide the bars or enter the values of the variables, and get the s-parameters and the geometry in real-time without re-simulating it. If you have different goals, you can select the Optim Goals tab and define your goals in the same way as you do it for the traditional IE3D optimization. You can also select the Zc tab to define the Zc of the ports. After you define the goals, you can slide the bars to see how the tuning variables to changing your geometry and the s-parameters. You can select the Optimize button to get the results in seconds. If you want to learn more about the process, please read the IE3D 12 manual or go to the www.zeland.com to watch a movie on the Zeland Virtual Training. Regards.